Capacitive sensors are used in a wide variety of applications, such as position sensing, material property monitoring, proximity switching, occupancy detection, fill level detection and measurement, and many others. Capacitive sensors can determine measurands that, in some way, affect the coupling capacitance between two or more electrodes. The capacitive sensors typically include measurement circuitry coupled to the electrodes. The measurement circuitry detects changes in the capacitance between the two or more electrodes. Although capacitive sensors typically measure capacitive coupling, in some applications relevant conductive components may be present.
One type of capacitive sensor is a seat occupancy sensor in an automobile. Seat occupancy sensors typically include large electrodes that may emit electromagnetic radiation that exceeds maximum allowable limits. Seat occupancy sensors and other capacitive sensors also typically include offset capacitances and offset conductances such that only a fraction of a sensed signal varies based on the measurands.
For these and other reasons, there is a need for the present invention.